The recognition specificity of antibodies for hitting a given target has been exploited for the diagnosis and therapy of various pathological conditions, and most particularly in the case of acquired immunodeficiency syndrome (AIDS), where the target can be a protein of human immunodeficiency viruses type 1 or 2 (HIV-1 and HIV-2).
In the context of the search for candidate antibodies for neutralizing an HIV protein, the inventors have oriented their studies toward particular antibodies, devoid of a light chain, identified in camelids (camel, dromedary, llama) (Hamers-Casterman et al., 1993).
Camelid single heavy-chain antibody variable domains (VHH), which specifically recognize one type of antigen, have been selected from an immunized animal and have been produced from plasmid constructs. As shown in the examples, these antibody fragments have been found to be capable of specifically targeting regions of the HIV Nef (negative regulatory factor) protein that are involved in the development of acquired immunodeficiency syndrome (AIDS).
The aim of the invention is therefore to provide single heavy-chain antibody fragments (also called sdAbs for single-domain antibodies), having the desired target and epitope recognition properties.
The aim of the invention is also to provide a method for producing these antibody fragments. According to yet another aspect, the invention is directed toward the immunotherapeutic applications thereof.